The use of blow molded plastic containers has become very commonplace in packaging beverages, such as juice. Blow molded plastic PET containers are particularly useful in the so-called "hot-fill" process, i.e. filling the containers with beverages at an elevated temperature, sealing the containers, and then allowing the beverage to cool. Blow molded plastic PET containers provide a package with sufficient flexure to compensate for the changes of pressure and temperature, while maintaining structural integrity and aesthetic appearance. In addition, the plastic used in the containers can be recycled. The production of commercial quantities of such containers can be done efficiently, quickly, and at a minimum of cost.
Smaller containers generally do not need handles because a consumer can grasp the sides of the container. However, larger containers, such as gallon containers, may require some form of handle in order for a consumer to control the container while carrying or pouring its contents. Some containers, such as milk bottles have handles blow molded integral with the container.
The attachment of separate handles onto blow molded PET containers presents a series of problems. The attachment must be strong enough so that it does not become detached either during the hot-fill process, or during transportation and handling. The attachment must be strong enough so that a consumer can lift and maneuver the container even in its completely filled condition. The container and handle should use a minimum of plastics to be cost effective. Finally, the attachment must provide an aesthetic appearance to the consumer.
There are several known methods of attaching separate handles to plastic blow-molded PET containers. Adhesives have been used to connect the handle to the container. Blow molded containers have been blown around portions of separate handles to connect the handle to the container. Handles have included straps which gird around the container sidewall and/or the container neck.
Ultrasonic welding horns have been used in the bottle art to bond various surfaces together. For instance, U.S. Pat. No. 5,275,767 relates to connecting the base of a container to a container sidewall; U.S. Pat. Nos. 5,256,225, 5,244,520, 4,726,481, and 4,746,025 relate to connecting nozzles, spouts and neck inserts to containers; and U.S. Pat. Nos. 5,040,357, 4,954,191, and 5,316,603 relate to connecting lids, covers or seals to containers.
Ultrasonic welding of a portion of a separate handle to a plastic container sidewall is disclosed in U.S. Pat. Nos. 4,273,246, 4,280,859, 4,368,826 and 4,372,454. A top portion of an L-shaped handle snaps onto the container neck and a bottom portion of the handle engages the container sidewall and can be attached with the use of ultrasonic welding.
Several problems exist which prevent effective bonds from being created between a separate handle and a blow molded plastic PET container, especially taking into account the size and weight of the container and the requirement that the bond be strong enough to resist detaching. The sidewall of a blow molded PET plastic container is flexible, and is required to be flexible in order to be used in the hot-fill process to compensate for changes in temperature and pressure. An ultrasonic welding horn typically vibrates in a range of some 20,000 cycles per second to effect melting of the surfaces of the two connecting parts. A significant degree of rigidity between the two connecting parts is needed in order to allow a bond to occur which will be strong enough to resist detachment when a gallon of liquid is lifted and poured.
Although various ones of the referenced containers may function satisfactorily for their intended purposes, there is a need for a blow molded plastic PET container and a separately attached service device, or handle, which is capable of being bonded together to resist separation even under the stresses imposed during handling and pouring a gallon of liquid. A method for attaching the handle and container with the use of ultrasonic welding horns is needed in which commercial quantities of bottles and attached handles can be produced efficiently, at a minimum of cost, and having superior aesthetic appearance.